Certain transition and heavy metal ions pose increasing environmental and health risks. Therefore, accurate quantification of toxic metal ions is important for environmental chemistry, biological chemistry and medical diagnostics. For example, as the use of Ni—Cd batteries increases, so does the prevalence of nickel and cadmium ions in manufacturing, disposal, and environmental contamination. It has long been known that mercury ions are a persistent and prevalent health risk, with a large percentage of the populace exposed to the risk. The same goes for lead ions, found in peeling paint on older buildings. These increasing incidences result in increasing exposures and internalization of these ions within individuals.
Paramagnetic lanthanides metal ions (including Lanthanum, Gadolinium, and Disprosium) enjoy numerous medical applications as contrast reagents in Magnetic Resonance Imaging (MRI). To overcome lanthanides toxicity they are converted into chelate complexes with polyamino acids, like EDTA and DTPA. However, some of the complexing reagents metabolize in vivo into non chelating species, resulting in free ion leakage. Therefore, determination of free lanthanides ions (both quantitatively and spatially) is an important task for this field.
Cadmium-based luminescent nanoparticles (Quantum Dots, QDs) are the part of the rapidly developing field of nanotechnology. In several biological labeling application QDs demonstrated certain advantages over conventional organic luminophores and already become a centerpiece of many biological labels, probes and techniques. However their applications for in vivo imaging and especially medical diagnostics are severely limited by the possible leaks of toxic cadmium ions. To facilitate the development of diagnostic applications based on QDs novel sensitive methods of Cd (II) ions analysis in biological objects are needed.
Thus there exists a need for increasingly sophisticated methods for the detection and quantitation of certain heavy metal and transition metal ions in a variety of samples, ranging from groundwater and soil to inside human cells. In the biomedical research field, luminescence-based probes of alkaline earth metal cations such as calcium have been of enormous benefit. To date there have been some examples of luminescence-based detection methods developed for heavy metal and transition metal ions. However these existing methods rely upon substandard compounds which lack specificity, dynamic range, sensitivity, and applicability to field use. The present invention addresses these shortcomings by describing novel luminescence-based materials that are very useful for the detection and quantitation of certain metal ions such as cadmium(II) and lanthanum.
The present invention addresses the problem of the ability to detect potentially toxic heavy metal cadmium and lanthanide ions in low concentration. The present compounds have better selectivity and sensitivity compared to indictors known in the art.